1. Field of the Invention
The present invention relates to a method and apparatus for adjusting the characteristics of a multi electron source having a number of surface conduction electron-emitting devices.
2. Related Background Art
Two types of electron emitting-devices are known, hot cathode devices and cold cathode devices. Known cold cathode devices include field emission devices (hereinafter described as FE), metal/insulator/metal emission devices (hereinafter described as MIME) and surface conduction electron-emitting devices (hereinafter described as SCE).
The present applicants have studied a multi electron source having a number of passive-matrix wired SCEs and an image display apparatus using such a multi electron source, as disclosed in Japanese Patent Application Laid-open No. 06-342636.
SCEs constituting a multi electron source have some dispersions in the electron emission characteristics because of process variations. If a display apparatus is manufactured by using such SCEs, dispersions in the characteristics result in dispersions in luminance. Japanese Patent Application Laid-open No. 10-228867 discloses the invention that dispersions in the SCE electron emission characteristics are removed by utilizing a memory capability of the SCE electron emission characteristics.
The present invention also relates to a technique of leveling the characteristics of a multi electron source by utilizing the memory capability of the SCE electron emission characteristics, similar to the above-described prior art (Japanese Patent Application Laid-open No. 10-228867), and provides an improved technique suitable for mass production of electron source panels.
According to the prior art technique, a characteristics leveling process incorporated in an electron source manufacture process is likely to have dispersions in adjustment times taken to adjust electron-emitting devices. There is therefore the possibility of dispersions in the adjustment times taken to adjust the characteristics of electron source panels and variations in adjusted electron emission characteristics.
The invention provides a manufacture process capable of manufacturing electron source panels having generally the same electron emission characteristics in generally the same process time even if the memory performance of the electron emission characteristics of SCEs constituting a multi-electron source is different among electron-emitting devices or among electron source panels.
An object of the invention is therefore to provide a method and apparatus for adjusting the characteristics of multi electron sources with simple processes, the multi electron sources having generally the same electron emission characteristics and adjusted in generally the same adjustment time.
According to the invention, prior to adjusting the characteristics, initial electron emission currents of all devices are measured to set a characteristics adjustment target value. By using some devices, the emission current change characteristics are measured at characteristics shift voltages. In accordance with an average of the measured characteristics, a characteristics adjustment table is created. Next, by referring to the characteristics adjustment table, the pulse peak and width of the characteristics shift voltage and the number of pulses to be applied to each device are determined to perform characteristics shift driving for removing a characteristics shift amount which is a difference between an initial electron emitting current and a characteristics adjustment target value. A change in electron emission characteristics during the characteristics shift driving is monitored to set again, when necessary, the characteristics shift conditions including the pulse peak and width and the number of pulses of the characteristics shift voltage.